A worthwhile upgrade to keep your clutch from becoming fouled with gearbox oil.

Install DynoDave clutch push rod seal for reliable smooth operation of the clutch, the clutch plates need to be free of gearbox oil. Unfortunately  the Norton design allows oil to weep down the clutch push rod. There are various approaches to fixing this, but the DynoDave clutch rod seal seems the best to me.  You can find out more about it here - http://atlanticgreen.com/store.htm. It's simple and effective.

It shown here mounted - its on top of the clutch retaining nut.